This invention relates to power circuits for quasi-steady plasma thrusters and in particular to the implementation of such circuits with self excited Hall effect switching means.
Various space missions such as satellite orbit control and spacecraft maneuvering would benefit from high specific impulse, high thrust density plasma thrusters. Although the use of plasma flows for such spacecraft propulsion and satellite maneuvering has been discussed and demonstrated, a practical application of the technique has not been realized. This is because a basic limitation on the use of electrically created plasma flows for such thruster applications is the need for electrical power suitable for driving the plasma thruster. That is, in order to achieve the advantages of high efficiency in plasma thrusters it is important to operate at high power levels. In particular, steady operation of plasma thrusters at high efficiency requires steady power levels in the megawatt range, which is usually beyond spacecraft capabilities. This problem of limited total spacecraft power can be overcome by employing a train of quasi-steady current pulses at high power, with interpulse times adjusted to match the available, steady electric power. Such repetitive pulsed operation requires power conditioning to provide high power pulses from low power steady sources. In earth-based laboratory environments, various techniques, such as oil-filled or electrolytic capacitor banks in pulse-forming networks, including triggered spark-gaps, have been used for electric thruster research and development. For spacecraft applications at high power levels and long mission-durations, such laboratory techniques are not satisfactory because of weight limitations and reliability. That is, the principal limitations and/or disadvantages of older methods may be summarized as: high weight and volume for capacitive energy storage; and, complexity (therefore low reliability) for repetitive, high voltage spark-gaps and related circuitry for producing a train of high power pulses.
Accordingly, power circuitry that is not subject to these limitations is needed to convert steady electrical power to a train of high power pulses. Such circuitry must be compact and lightweight in order to satisfy mission constraints. The power circuits based on the Hall effect, comprehended by the present invention, can provide the necessary power conditioning for spacecraft applications, quasi-steady plasma thruster research, and, incidentally, other applications requiring pulse trains at megawatt power levels.